A conventional cable connection structure of this kind is illustrated in FIG. 19. In FIG. 19, the conventional cable connection structure includes a holder 50, a plurality of round cables W1 held by the holder 50, a flat cable W2 held by the holder 50, and a mold resin portion 51 covering the outer circumference of the holder 50.
The plurality of round cables W1 and the flat cable W2 held by the holder 50 overlap each other at the end portions thereof, and are pulled out in mutually opposite directions. Core wires (not illustrated) at end portions of the round cables W1 and conductors (not illustrated) at an end portion of the flat cable W2 are connected to each other by connecting portions 53 formed by ultrasonic welding or the like.
The mold resin portion 51 collectively covers the holder 50 and the round cables W1 and the flat cable W2 pulled out from the holder 50. Accordingly, the portion including the connecting portions 53 is waterproofed by the mold resin portion 51.
The core wires (not illustrated) of the round cables W1 and the conductors (not illustrated) of the flat cable W2 are connected by, for example, ultrasonic welding using an ultrasonic welding device 30, as illustrated in FIG. 20. The ultrasonic welding device 30 includes an anvil 34 that places the holder 50 in a positioned state, and a horn 33 that applies, while applying pressure, ultrasonic vibration (in the direction of the arrow in FIG. 10) to the position in which the core wires (not illustrated) of the round cables W1 and the conductors (not illustrated) of the flat cable W2 overlap each other. The horn 33 is provided at the distal end of an arm portion 32 whose base end portion is supported by a device main body 31.
Incidentally, when the holder 50 holding the round cables W1 and the flat cable W2 is set in the ultrasonic welding device 30, the round cables W1 may have to be set away from the ultrasonic welding device 30, and the flat cable W2 may have to be set in the space between the horn 33 and the device main body 31 in some cases. For example, in a case where the round cables W1 compose a long wire harness (not illustrated), the wire harness (not illustrated) may not be set in the space between the horn 33 and the device main body 31.